NEUROPTHRA. 417 
vulgata, Fig. 389), is of a brown colour, banded with yellow, and 
the wings smoky, with brown spots. These insects are remarkable 
for their elegant flight; they are continu- Z 
\ f 
\ / 
ally rising and falling. When they move 
their wings, they rise; but if their wings, 
though spread out, remain motionless, as 
also the silky hairs which form their tail, 
they fall again. They may be seen in 
myriads in places where there is much 
water. 
We have said that the Ephemere live 
only for a few hours. This is the general 
rule; but their existence can be prolonged 
for ten or fifteen days by preventing their 
copulation. If, however, the duration of 
the life of these insects is so short when 
they have reached the perfect state, and 
when the conformation of the mouth pre- 
vents them from taking any nourishment, 
their larva state is of very long continu- 
ance. Swammerdam says, in his curious | 
memoir, entitled ‘“ Vita Ephemeri,” it is Fig. Rta 
not less than three years. 
The females lay their eggs in one single mass, and let them 
fall into the water, in the form of a packet. The larve which 
come out of them are very active, and swim with great ease; but 
generally conceal themselves under the pebbles at the bottom. 
The sides of their abdomen are provided with gills, very much 
fringed, which serve them, not only for breathing the air under 
the water in the same way that fish do, but also for swimming. 
The larve have, at the extremity of their body, two or three 
hairs, like the perfect insect. They hollow out galleries in the 
beds of rivers and ponds, and live on small insects. The pupa 
(Fig. 391) differs only from the larva (Fig. 390) in having the 
rudiments of wings. When about to undergo their metamor- 
phosis, they come out of the water and cling to plants, &. The 
skin cracks on the back when it is dry, and there comes out a 
heavy insect, which flies feebly, and has opaque wings. It is 
EE 

